If fireworks were strictly gunpowder, there’d be no excitement, really. They’d all just be balls of fire in the air.

Salts and other metal compounds allow a firework to detonate in bursts of bright blue or rich red. To make red, fireworks contain strontium salts and/or lithium salts, with the strontium producing a brighter red reaction. Calcium salts make orange, while sodium salts (as in table salt) explode in yellow. Green comes from the compound barium chloride, blue from copper chloride.

Silver or white colors are made of aluminum or magnesium. If you want purple, you have to work a little harder: Combine strontium salts for red and copper chloride for blue to create a purple explosion.

These star patterns are basically the prenatal image of a star-shaped firework. Each half of the shell will contain identical parts and when both halves are joined, the sides mirror each other.

Sparklers
Because sparklers are governed under the same laws as fireworks, we’ll include them even though they’re technically considered novelties.

Sparklers consist of several compounds that when mixed, create a slurry into which the body of the sparkler is dipped. This coating is what burns and produces the bright light that sparklers emit. The fuel and oxidizer are added in specific proportions so that the sparkler doesn’t explode like a traditional firework, but instead burns much more slowly (and safely).

The first thing you should know about Roman Candles is that, contrary to popular belief, they’re not meant to be held in your hand.

Roman Candles are banned in some places because people tend to use them the wrong way. In Delaware, it’s illegal to have them at all and in Wisconsin, you have to have a permit to purchase and use Roman Candles.

The candles are essentially cardboard tubes in wrapping paper. A lit fuse makes its way to a lifting charge that builds pressure and pushes the stars out, setting them off. Roman Candles usually feature a couple of stars within the tube separated by a delay (or powder) charge that spaces the explosions out.

To ensure that the flame doesn’t reach the next star before all of the powder has been burned away, the powder gets tightly packed. This helps avoid misfirings.

Whoever produced these stars has mastered the barium chlorate concoction that gives fireworks the toxic-green sheen of Ghostbusters‘ Slimer. The green bee trajectories are the random product of stars packed into small tubes (3 inches long x ½ inch diameter) within a spherical shell. As the heat increases, the pressure in the tube sends the stars zipping out haphazardly.

“To have a star composition in these tubes is almost like having rocket powder,” says Jim Souza of Pyro Spectaculars in Rialto, California.

Pyrotechnicians agree that the blue-violet shades of this peacock feather are the most challenging to formulate. The concentrations of chemicals used to make vivid violet blues are unstable and extremely dangerous. In this case, copper oxide and strontium carbonate get the job done. Gold pellets are placed circumferentially at the shell’s equator to create a golden Saturn ring.

The single tail star has a shorter time delay fuse, causing the star to ignite at the same time as the lift charge at takeoff. Once the shell reaches its zenith, the bursting charge ruptures the shell casing and Saturn emerges.

The guts of this firework must be carefully placed into a cylindrical shell about the size of a Quaker Oats canister, Souza says. In the center of the shell are tiny round green stars that burst as a teal peony at the firework’s nucleus.

Larger gold comet stars border the teal pellets and flare out when ignited, eventually peeling off into sharp scarlet quills. The animation can be changed by inserting scarlet stars into special compartments at the outskirts of cylinder.

Each cosmic red tendril and teal plume has a matching pyro pellet within the firework shell. The teal stars are made of a barium nitrate mixture and the red stars are a blend of strontium salts.